Process for printing thermoplastic materials

ABSTRACT

A process is disclosed for transfer printing thermoplastic materials with thermal diffusion inks. An image is transferred in a heatable press from a paper substrate colored with thermal diffusion inks onto an intermittently moved, fiber-containing carrier material into which the thermal diffusion inks can at first be sublimated then diffused. This fiber-containing carrier material provided with thermal diffusion inks is then transported into the gap between the calender rollers, where it is continuously brought into contact with a thermoplastic melt at an increased temperature so that the thermal diffusion inks penetrate into the thermoplastic melt and at the same time a composite strip made of the fiber-containing carrier material and the thermoplastic melt is formed. The products obtained by this process are suitable for producing a decorative layer on parts of skis or snowboards and on composite materials made of fiber-reinforced plastics.

BACKGROUND OF THE INVENTION

The invention relates to a process for printing thermoplastic materialswith thermodiffusion dyes by transfer printing as well as theadvantageous use of the product manufactured in this manner.

DESCRIPTION OF RELATED ART

It is known from DE-OS 2 731 121 that thermoplastic materials such aspolyethylene can be printed by bringing the side of the polyethylenebody which is to be printed under the influence of heat, and the meltingeffect caused thereby, into contact with a print carrier such as a papersubstrate provided with thermodiffusion dyes. The printing of thedecoration from the paper carrier onto the polyethylene body occurs attemperatures of 160° to 220° C., and the thermodiffusion dyes are firstsublimated and then diffused into the thermoplastic material. With thisprocess, however, the decorations printed on the thermoplastic materialhave blurred border zones, since the dyes migrate (bleed) in thepolyethylene. This leads, especially under UV-ray influence, to a lossof color brightness or to the total loss of the decoration. Furthermore,great thermal tensions are liberated through the melting of the surfaceto be printed, and this does not permit the printing of relativelythin-walled objects, for example, strip-shaped objects such as skilinings, without a previous preparation for obtaining a balance of theinner tensions.

In this manner, an extreme tension decay occurs in the area of theborder line between the molten side to be printed and the undersidewhich is still in solid condition, and this leads to a warping of theprinted lining during cooling. The melting in the case of previouslytreated ski-lining materials, that is, sharpened and gas-blazedski-lining materials, causes a further deterioration of the mechanicalproperties already obtained, such as the pull force.

SUMMARY OF THE INVENTION

The present invention has, therefore, as its object to provide a processof the kind described above which allows bright contour-sharp,distortion-free prints without causing any rejection problems ordeteriorated mechanical properties after the color transfer. Theinvention proposes a process for printing thermoplastic materials withthermodiffusion dyes by transfer pressure, wherein a print picture isproduced by means of a paper substrate provided with thermodiffusiondyes which are sublimable at first and then diffusible into anintermittently moving carrier material containing fibers, and whereinthis fiber-containing carrier material with the thermodiffusion dyes iscontinuously brought into contact with a thermoplastic melt through acalender roller gap in such a manner that the thermodiffusion dyespenetrate into the thermoplastic material and, at the same time, form astrip-shaped composite consisting of the fiber-containing carriermaterial and the thermoplastic material. With the process according tothe invention, a bright contour-sharp print is generated on thethermoplastic material which is also color-stable with respect to UVrays, partially due to the penetration depth of the thermodiffusion dyesinto the thermoplastic material. The printed thermoplastic material alsohas a high shape stability as well as especially good mechanicalproperties partially due to the fiber-containing carrier material.

Other advantages of the invention are caused by the fact that a fiberfabric, weave, or fleece is used as fiber-containing carrier material.The fibers in the carrier material are artificial and/or natural fibers,whereby the artificial fibers are made of polyester and/or polyamide andthe natural fibers are cotton fibers. By taking these measures, nothermal shrinking occurs in the fiber-containing carrier material up to200° C.

The invention is further characterized in that the fiber-containingcarrier material is provided with an adhesive means on one or bothsurface sides that can be a hot melt adhesive film.

A further advantage of the invention consists in that polyethylene orpolyamide is used as thermoplastic material.

The invention further relates to the use of a thermoplastic materialprinted with thermodiffusion dyes for manufacturing a decoration liningfor ski or snowboard parts as well as for manufacturing a decorationlayer on plastic-fiber attachment materials.

DESCRIPTION OF THE FIGURES OF DRAWINGS

The invention is further explained with respect to FIGS. 1 and 2 as wellas with respect to the embodiments.

FIG. 1 shows a schematic of an apparatus and the process for printingwith a paper substrate provided with thermodiffusion dyes on thefiber-containing carrier material.

FIG. 2 shows a schematic of an apparatus and the process for forming astrip-shaped composite consisting of the fiber-containing carriermaterial and the thermoplastic material where the thermodiffusion dyespenetrate into the thermoplastic material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The process according to the invention will be further explained withrespect to the following embodiments as well as the descriptionaccording to FIGS. 1 and 2.

According to FIG. 1, the fiber-containing carrier material 2 which, forexample, can be a polyester fleece, is guided from the storage roll 1into a heatable press 3. The carrier material has a needed width that isadvantageous for its further use, such as the usual width of skis.Furthermore, it can be provided with a melt adhesive means on one orboth surface sides. The fiber-containing carrier material 2 can be easedinto the heatable press 3 partially by hand with a paper 4 provided withthermodiffusion dyes 4'. The length of the paper depends on the furtherintended use; it can correspond, for example, to the usual length of aski. Additionally, the press 3 can be closed and heated to approximately190° C. The time that the carrier material stays in the press can befrom 30 to 210 seconds. The print pressure amounts to 80 to 85 bar.Because of the high temperatures in the heatable press, thethermodiffusion dyes 4' are sublimated in such a way that--due to thepressing pressure of the press plates 5, 6--the printing of thedecoration 4' of the paper 4 occurs on the carrier material 2. Thefiber-containing carrier material 7 provided on the decoration side 7'provided with the thermodiffusion dyes 4' is rolled about the roll 8 andcan be stored or conveyed to the next process step.

This further use takes place according to FIG. 2 in that the storageroll 8 is placed ahead of a three-roll calender 9, whereby thefiber-containing carrier material 7 with the decoration side 7' providedwith transfer pressure colors 4' is guided to the calender roller 9aheated to a temperature of 128° to 130° C. The decoration side 7' of thefiber-containing carrier material 7 with the thermodiffusion dyes 4'faces away from the calender roller 9a. At the same time, athermoplastic melt 11 coming out of the extruder nozzle 10 is guidedinto the roller gap 12 created between the calender rollers 9a and 9b sothat the substrate material 7 provided with the thermodiffusion dyes 4'and the thermoplastic melt 11 can come into contact. A composite 13consisting of the fiber-containing carrier 7 and the thermoplasticmaterial 11 is formed due to the higher temperature existing in theroller gap 12 and the print pressure generated by the calender rollers9a and 9b and the transfer pressure colors 4' have already mostly beensublimated and have penetrated into the thermoplastic material 11.Polyethylene, for example, can be used as thermoplastic material 11, butit can also be a thermoplastic mixture of polymers of differentstructure. Further, and as a consequence of this, the composite 13 isguided to the roller gap 14 of the calender roller 9c created betweenthe calender rollers 9b and 9c so that the calender rollers 9b and 9ccan generate, on the one hand, an adhesive composite 13 consisting ofthe thermoplastic material 11 and the fiber-containing carrier material7 by means of the temperature held at a constant 60° to 70° C. and theimpression pressure generated in this way, and, on the other hand, thethermodiffusion dyes can be completely sublimated through thetemperature, which is held constant, and can penetrate into thethermoplastic material 11. The penetration depth amounts to 0.1 to 0.2mm. Further, the composite 13 is shaped and cooled down simultaneouslyby means of the temperature gradients formed between the calender roller9a and the roller 9b. In this way, a thermoplastic material strip 15printed with the thermodiffusion dyes 4' is manufactured and brings outthe decoration with satisfactory contour sharpness and additionallyshows improved mechanical properties due to the measure of usingfiber-containing carrier material. The decorated thermoplastic materialstrip 15 can, additionally, be guided via the transport roller pair 17to the storage roll 16 and, if necessary, can be trimmed with the crosscutter 18 for manufacturing individual articles.

The thermoplastic material strip decorated with thermodiffusion dyesmanufactured according to the invention can be used for manufacturing adecoration layer on ski or snowboard parts and technical composites suchas fiber combinations impregnated with epoxy resin as well asthermoplastic resins reinforced with fibers. The thermoplastic materialstrip can be attached to each decorated part by the usual adhesivetechniques.

I claim:
 1. Process for printing thermoplastic materials withthermodiffusion dyes by transfer printing comprisinga) producing in aheatable press a printed picture on an intermittently movingfiber-containing carrier material by picture transfer from a papercarrier provided with thermodiffusion dyes which are first sublimableand then diffusible and b) guiding the fiber-containing carrier materialprovided with the thermodiffusion dyes into a calender roller gap atelevated temperature and bringing it continuously in contact with athermoplastic material in such a manner that the thermodiffusion dyespenetrate into the thermoplastic material and, at the same time, createa strip-shaped composite consisting of the fiber-containing carriermaterial and the printed thermoplastic material.
 2. Process according toclaim 1 wherein the fiber-containing material is a material selectedfrom the group consisting of a fiber fabric, weave, or fleece. 3.Process according to claim 2 wherein the fibers in the carrier materialare selected from the group consisting of artificial fibers, naturalfibers and mixtures thereof.
 4. Process according to claim 3 wherein theartificial fibers are selected from the group consisting of polyesterpolyamide and mixtures thereof.
 5. Process according to claim 3 whereinthe natural fibers are cotton fibers.
 6. Process according to claim 1wherein polyethylene is used as the thermoplastic material.
 7. Processaccording to claim 1 wherein polyamide is used as the thermoplasticmaterial.
 8. A thermoplastic material printed with thermodiffusion dyesmanufactured according to claim 1 for manufacturing a decorative layeron ski or snowboard parts.
 9. A thermoplastic material printed withthermodiffusion dyes manufactured according to claim 1 for manufacturinga decorative layer on a fiber reinforced plastic compound.